Holders and holder details for plastic moulding tools are employed as clamping and/or framing components for the plastic moulding tool in tool sets, in which tool the plastic product shall be manufactured through some kind of moulding method. Among conceivable holder details there can be mentioned bolster plates and other construction parts as well as heavy blocks with large recesses which can accommodate and hold the actual moulding tool. Said holders and holder details are made of many different steel alloys, including martensitic stainless steels. A steel which is manufactured and marketed by the applicant under the registered trade name RAMAX S® belongs to that group and has the following nominal composition in weight-%: 0.33 C, 0.35 Si, 1.35 Mn, 16.6 Cr, 0.55 Ni, 0.12 N, 0.12 S, balance iron and impurities from the manufacturing of the steel. The closest comparable standardized steel is AISI 420F. Steels of this type have an adequate corrosion resistance, but do not have a martensitic micro-structure which is as homogenous that is desirable, but may contain ferrite and hard spots, which are due to retained, untempered martensite, which in turn can be explained by a certain segregation tendency of the steel. Therefore it exists a demand of improvements as far as holder steels are concerned. It is also desirable that the same steel, possibly with some modification of the composition, also shall be useful for the actual moulding tool.